Coin controlled telephone system



R. PRICHARD COIN CONTROLLED TELEPHONE SYSTEM June 26, 1962 Filed June 25, 1959 R. D m R N m m m m R kzwzmsow Y 85% #Q S ZQFEQE m m l l fi l l kk l... u 2.3% 0K. Z8 v8.6 28% \IJ 322% a ll) M33; in W J x M F 1 W H v hzmsES 321% mziutaw 2522a. SGQEQ 2.8 I N @565; 260

ATTORNEY 3,041,358 CQIN CONTROLLED TELEPHONE SYSTEM Roy Prichard, River Grove, Ill, assignor to international Telephone 8: Telegraph Corporation, New York, N.Y., a corporation of Maryland Filed June 25, 1959, Ser. No. 822,969 7 Claims. (Cl. 1796.3)

This invention relates to coin controlled telephone systems and more particularly to means for detecting coins deposited at paystation telephones.

It is old in the art of coin controlled telephony first, to provide means for discriminating between the presence of coin indicating potentials and other potentials which may be applied in simulation thereof, and second, to provide means for extending certain calls on a free service basis and other calls on a pay basis. However, circuits for accomplishing these ends have been unduly complicated, thereby causing severe economic disadvantages because such circuits are generally provided on a one-perpaystation basis-and paystations are the most numerous items in a coin controlled telephone system. Therefore, there is a need for simple, inexpensive, and easily in stalled devices for discriminating between coin applied and other potentials and for detecting free service calls, whereby such calls may be completed without the deposit of a coin.

An object of this invention is to provide new and improved coin controlled circuitry.

Another object of this invention is to provide means for detecting fraudulently applied, coin simulating potentials.

Yet another object of this invention is to provide means for allowing free service calls without requiring the deposit of a prepay coin.

Still another object of this invention is to provide means for detecting fraudulent, coin simulating potentials and for giving free service calls by means of simple and inexpensive devices which may be installed with a minimum of efiort.

In accordance with this invention, the only modifications which are required at paystations of conventional, present day design include the removal of coin controlled springs which shunt dial impulsing contacts and the addition of a rectifier across other coin operated springs. Since dial springs are no longer shunted, a call may be placed at a paystation as from any non pay or free service station. It the numerical value of the first digit pulse train indicates a free service call, it may be completed in any well known manner. However, if the numerical value of the first digit pulse train indicates a pay call, a coin test device is connected to one side of the line. The rectifier is connected between the test device and coin springs and is poled to block a properly applied coin potential; therefore, the test device does not respond and a call is completed in a normal manner. If a fraudulent, coin simulating potential is present, the rectifier is shunted by non-operated coin springs, the test device operates, and the call is released.

The above mentioned and other objects of this invention together with the manner of obtaining them will become more apparent and the invention itself Will be best understood by making reference to the following description of an embodiment of the invention taken in conjunction with the accompanying single sheet of drawings which shows a portion of a paystation and central office equipment adapted to respond to coin control.

Where possible, simple terms are used and specific items are described hereinafter to facilitate an understanding of the invention; however, it should be understood that the use of such terms and references to such items are not to act in any manner as a disclaimer of the full range of fidlfifid Patented June 26, 1%62 equivalents which is normally given under established rules of patent law. For example, rectifier 5 is shown as a semiconductor; whereas, any uni-directional conductor may be used if poled as indicated to block coin indicating potential extended through contacts 3. In a similar manner, dial springs 7 provide for loop pulsing; whereas, any suitable digit signalling device may be used. Moreover, contacts 3 and 4 are shown as springs which may be closed responsive to the weight of a properly deposited coin; whereas, any suitable coin detection means may be used. Quite obviously, otherexamples could be selected to illustrate the manner in which the terms used and items described hereinafter are entitled to a wide range of equivalents.

Those portions of the paystation and central ofilce equipment which are not shown may assume any well known design.

Item 8 represents a fraudulently applied ground potential which simulates a deposited coin. Normally, there is no such ground potential; detection of it is the objective of the present circuit. a

A call is initiated by a subscriber who removes a handset or receiver, thereby closing hookswitch contacts 13 in any well known manner to complete a loop which may be traced from battery through the upper winding of relay 9, dial impulse springs 7, rectifier 5, contacts 13, 10 and the lower winding of relay 9 to ground potential. The seizure signal is the same whether a coin has or has not been deposited to open contacts 4 and close contacts 3.

The calling subscriber proceeds to dial a first digit by causing dial impulse springs 7 to open and close a predetermined number of times responsive to the motion of a telephone dial. Each time that the loop is opened and closed by dial impulse springs 7, line relay 9 releases and reoperates to transmit switch controlling signals through contacts 14. Responsive thereto automatic switching equipment 17 is driven to seize and signal the called line in any well known manner.

Means is provided for discriminating between free service and pay calls. That is, any suitable telephone switching equipment 17 responds to the control signals which are repeated at contacts 14 under the influence of a first digit pulse train. If the numerical value of the first digit pulse train indicates that a free service call is being initiated, contacts 10 remain closed and the call may be completed in a well known manner. On the other hand, if the numerical value of the first digit pulse train indicates that a pay call is being initiated, any suitable means may operate to open contacts 10 and close contacts 11, thereby discriminating between free service and pay calls by connecting a coin test device (ground check relay 12) to the line. The means for operating contacts 10 and 11 may take any suitable form Such as a relay l8 operated responsive to level marking apparatus 19 in step-by-step equipment, a relay operated from a register, a relay operated by a special counting device which responds to the first digit pulse train, etc. As shown in the drawing, relay 18 operates on all except the tenth or zero level of bank 19 when ground on wiper 2d energizes the winding thereof.

If it is assumed that a coin is properly deposited, that there is no fraudulent coin simulating potential, and further that the first digit does not indicate a free service call, line relay 9 is held operated by a circuit which may be traced from battery through the upper winding of relay 9, contacts 7, 3, and the windings of coin magnets 2 and 1 to ground. When relay 18 operates, contacts 11 close and a test or ground check relay i2 is connected to the lower side of the line; however, there is no effect since contacts 4 are open and diode 5 is poled to block the flow of current from ground through the windings of magnets 1 and 2, contacts 3, diode 5, contacts 13, 11 and the winding of relay 12 to battery. With relay 9' operated and relay 12 unoperated, the call is completed in a conventional manner.

If it is assumed that no coin has been deposited but a fraudulent, coin simulating potential is present, contacts 3 are open and contacts 4 are closed; therefore, line relay 9 is held over the circuit which may be traced from battery through the upper winding of relay 9, dial springs 7, closed contacts 4, 13, and a coin simulating ground potential extended through resistance 8. Ground check relay 12 also operates over a circuit extending from coin simulating ground potential through resistance 8, closed contacts 11, and the winding of relay 12 to battery. It the fraudulent, coin simulating ground potential were applied at point 16 instead of through resistance 8 (as shown), thecircuit for operating ground check relay 12 could be traced from point 16 through contacts '7, 4, 13 and 11 to battery through the winding of relay 12. Responsive to the operation of relay 12, contacts 15 close, thereby releasing central office equipment in any well known manner. Contacts 15 may also be arranged to give an alarm, as required.

Next, let it be assumed that no coin has been deposited, that a pay call is initiated, and further that no coin simulating potential is applied to the line. Contacts 3 are open and contacts 4 are closed. At the end of the first digit pulse train, means relay 18 in the central office opens contacts and closes contacts 11. Therefore, the loop is broken and line relay 9 restores. Responsive thereto, central office equipment is released as when a receiver or handset is replaced to open hookswitch contacts 13.

If it is assumed that there is both a proper coin indicating potential and an improper coin simulating potential, it is an indication of trouble-not an indication of an attempt to defraud the telephone company. The problem, therefore, is one of providing maintenance.

Thus, it is seen that the subject circuit provides means for extending free service calls which may be identified by the numerical value of a first digit, for providing a positive coin check on all other calls, and for transmitting of an alarm or release signal as required if a fraudulent, coin simulating potential is present.

While the principles of the invention have been described above in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of the invention.

I claim:

1. In a coin controlled telephone system, means for discriminating between free service calls and pay calls, means responsive to the detection of pay calls for testing to determine whether a coin has been deposited, means responsive to a signal indicating a-properly deposited coin for completing said pay calls, means responsive to coin simulating signals for releasing said pay calls, means responsive to detection of free service calls for preventing said coin test, a two conductor telephone line, a line relay connected to be operated responsive to closed loop conditions on said line, and a coin test relay, said means for testing to determine whether a coin has been deposited comprising means for breaking said closed loop condition and connecting said line relay to be held responsive to said properly deposited coin signal applied to one of said conductors, and means for connecting said coin test relay to the other of said conductors to be operated responsive to said coin simulating signal. 7

2. The telephone system of claim 1 and control means connected to prevent operation of said coin test relay responsive to said properly deposited coin signal.

3. The telephone system of claim 2 wherein said properly deposited coin signals are transmitted from coin springs, and said control means comprises a rectifier connected to block current flow between said coin springs and said coin test relay.

4. The telephone system of claim 3 wherein said rectifier is connected to be shunted by said coin operated springs when in an unoperated position.

5. In a telephone system, a two conductor telephone line having a paystation coupled to one end thereof and a line relay coupled to the other end thereof, means responsive to a coin deposited at said paystation for applying a potential to one of said conductors to hold said line relay in an operated condition, a test relay, means for disconnecting the other of said conductors from said line clay and for connecting said other conductor to said test relay, and means comprising a rectifier coupled to block current flow from said coin applied potential to said test relay.

6. The telephone system of claim 5 wherein said coin responsive means comprises a plurality of contacts which are operated responsive to a deposited coin, one of said contacts being connected to shunt said rectifier. when a coin is absent and another of said contacts being connected to apply said potential when a coin is. present.

7. A prepay station having coin controlled contacts for applying a potential to a telephone line responsive to a properly deposited coin, a rectifier bridged across said coin controlled contacts, said rectifier being poled to prevent fiow of said potential over one conductor of said line, and means connected to said one conductor to be operated responsive to fraudulent potentials applied in simulation of said coin controlled potential.

References Cited in the tile of this patent UNITED STATES PATENTS 2,082,097 Cesaro June 1, 1937 2,248,575 Lornax July 8, 1941 2,700,069 Pharis et al. Jan. 18, 1955 2,860,184 Lornax Nov. 11, 1958 2,921,980 Lomax Jan. 19, 1960 

